The Sitcom Behind the Sitcom : Television: The countdown to an 'Evening Shade' rehearsal can be comedic. Just ask writer and producer Linda Bloodworth-Thomason.

To those people in Hollywood who fill up empty computer screens writing comedy and drama, Linda Bloodworth-Thomason is an amazement. She has written 61 "Designing Women" scripts in the past four years, most of them scrawled on yellow legal pads the Saturday and/or Sunday before the first cast rehearsal on Monday. That's like running the three-minute mile in spike heels.

"I used to take six to eight hours on a script," she says. "Now I take about 12 to 14 hours. I'm going downhill. . . .

"Of course," she adds, "a lot of writers will read this and wonder, 'Who does this broad think she is?' Listen, not all these are gems."

But "Designing Women," a monster hit for CBS (No. 6 for the season), is widely regarded as one of the best-written series on the air, and Bloodworth-Thomason is now applying her talents to "Evening Shade," the new Burt Reynolds comedy. She created the show and produces it with husband Harry Thomason.

CBS will re-introduce the series in a different time period tonight at 8, spelling "Uncle Buck" for the week. "Evening Shade" will also play at 8 p.m. Friday, its usual time slot.

"Evening Shade" ranks 57th in the season-to-date ratings (out of 90 prime-time series). But, cautioned Michael Eisenberg, CBS vice president for audience measurement, ensemble series are notoriously slow to build an audience. If the episode tonight does "substantially well," a shift in time period might be recommended.

Despite the legend growing up around Bloodworth-Thomason's writing feats, the preparation of tonight's "Evening Shade" episode, called "Fast Women," turned out to be a sitcom within a sitcom. The episode took 12 to 14 hours to write, spread over three days instead of the usual two, because of digressions.

She waxed philosophic late one Monday night in September, knowing that the cast would be waiting for her words the next morning: "The interesting thing is that when you have five hours to write 30 more pages and these people are here from Poplar Bluff (her Missouri hometown) and your brother told them that you personally are gonna give them a tour of the whole lot and there's a reporter on the phone asking you to comment on Burt and it's for USA Weekend and the hairdresser did not work out and two of the actors didn't get here from Dallas for dubbing and you're just standing there with a big smile on your face . . . then you really know what it's like to be Miss Congeniality."

As for the plot: Wood Newton (Reynolds) is prevailed on by wife Ava (Marilu Henner) to intervene in the romantic pursuits of son Taylor (Jay R. Ferguson) and Ava's father, Evan (Hal Holbrook). Taylor is entangled with a senior who announces to Newton that she intends to "have sex with your son" and will be gentle. Evan is likewise entangled with the town stripper, who dances with a very long scarf.

By ready resume, Bloodworth-Thomason comes to her present position via the University of Missouri, the Wall Street Journal (selling ads), a high school in Watts (teaching), then "MASH," "One Day at a Time," "Rhoda," "Limestreet" and "Filthy Rich" (writing scripts).

She is an ebullient woman who talks considerably, and considerably like a composite of her "Designing Women" cast. She seems more earth mother than Hollywood producer.

Her talent is (1) writing and (2) putting off writing. "I get distracted very easily," she said.

On the Saturday afternoon that she commenced writing "Fast Women," before the series had made its debut, a friend called from Poplar Bluff with an hour of town gossip. Meanwhile, Burt Reynolds had been hammering on the walls of the show's office at MTM Studios in North Hollywood. "He's hanging photos of his life," she explained, "and now he's hanging them in my office and my bathroom--since he's out of space in his office. He is a hanging-picture fanatic."

Husband Harry brought in a deli feast for a picnic on the set. Pam Norris, who now produces "Designing Women" and does most of its writing, came by for more digression. Like the Miss America Pageant. "We just watch the part where the girls come in and shout their states," Bloodworth-Thomason said. "Then we're satiated."

She and Norris have an odd bond. Each needs a deadline hanging over her head like the sword of Damocles. Wherever they are on Sunday nights at 7, they yell when the ticking clock starts on "60 Minutes"--a ritual panic signifying that they're not ready for the messenger who's been dispatched by the script-typing service to collect their pages.

"Without Pam, there's no way I could do this new show," Bloodworth-Thomason said. "We shoot her scripts as they are. If I died tonight, I know that as a personal favor, she'd finish this script."

Sunday was dead for writing. CBS desperately needed the hour pilot to send to the press for reviews--and it was 24 minutes long! She spent day and night in the editing trailer. The cast was told to report for the week's script reading on Tuesday instead of Monday.